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GCN Circulars

GCN Circulars are rapid astronomical bulletins submitted by and distributed to community members worldwide. They are used to share discoveries, observations, quantitative near-term predictions, requests for follow-up observations, or future observing plans related to high-energy, multi-messenger, and variable or transient astrophysical events. See the documentation for help with subscribing to or submitting Circulars.

Search for Circulars by submitter, subject, or body text (e.g. 'Fermi GRB').
To navigate to a specific circular, enter the associated Circular ID (e.g. 'gcn123', 'Circular 123', or '123').
Advanced Search

To narrow the search results, use advanced search syntax. This allows for specifying which circular field to search (submitter, subject, and/or body). For additional information, refer to the advanced search documentation.

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subject:"Swift"
body:"GRB"
submitter:"Judith Racusin"

23442 results found.

  1. EP250428b: FTW optical and NIR observations
  2. EP250427a/GRB250427A: HCT optical follow-up
  3. SVOM/sb25043004: SVOM detection of a X-ray transient
  4. EP250428b: GROWTH-India telescope optical upper limit
  5. EP250428b: SVOM/VT upper limit
  6. EP250428b: SAO RAS optical upper limit
  7. EP250428b: LAST optical upper limit
  8. GRB 250427A: Swift/UVOT Detection
  9. EP250428b: Einstein Probe detection of a fast X-ray transient
  10. EP250427A: COLIBRÍ Continuing Optical Observations
  11. GRB250427A/EP250427a GIT optical afterglow detection:
  12. EP250427a: LT optical counterpart detection
  13. GRB 250427A: Swift-XRT refined Analysis
  14. EP250427a / GRB 250427A: LCO optical counterpart detection
  15. EP250427a: REM optical/NIR afterglow detection
  16. GRB 250424A: LCO optical observation
  17. EP250427A: COLIBRÍ Optical Detection
  18. EP250427a: TRT optical counterpart detection
  19. EP250427a: Einstein Probe detection of a fast X-ray transient
  20. GRB 250424A: SVOM/GRM observation of a long burst
  21. GRB 250424A: PRIME near-infrared detection
  22. GRB 250424A: WINTER J-band detection
  23. GRB 250419A: Mondy Optical Observations
  24. GRB 250424A: Swift/UVOT Detection
  25. Konus-Wind detection of GRB 250424A
  26. GRB 250424A: Skynet Optical Observations
  27. GRB 250424A: Kilonova-Catcher optical afterglow detection
  28. GRB 250419A: Liverpool Telescope optical upper limit
  29. GRB 250424A: Enhanced Swift-XRT position
  30. GRB 250424A: AstroSat CZTI detection of a bright long burst
  31. GRB 250424A: COLIBRÍ Detection of a Bright Optical Counterpart
  32. GRB 250424A: BlackGEM optical afterglow detection
  33. GRB 250424A: DDOTI Afterglow Detection
  34. GRB 250424A: REM optical/NIR afterglow detection
  35. GRB 250424A: Swift detection of a burst with an optical counterpart
  36. LIGO/Virgo/KAGRA S250328ae: Subaru/PFS Spectroscopic Follow up and Candidates
  37. EP250421a: Nickel optical upper limit
  38. SVOM/sb25042207: XRT observations
  39. GRB 250421A: AstroSat CZTI detection
  40. IceCube-250421A: DDOTI Detection of the LAST Candidate
  41. GRB 250419A: Mephisto Multi-band Optical Detection
  42. GRB 250419A: Calapai Observatory, Massa S. Giorgio (Messina), optical observations.
  43. IC-250421A: LAST optical observations of the IceCube neutrino candidate
  44. EP250421a: NOT optical observations
  45. GRB 250419A: Optical Observations via Virtual Telescope Project
  46. EP250421a: REM optical upper limit
  47. EP250421a: Swift/XRT counterpart detection
  48. EP250421A: COLIBRÍ Optical Upper Limit
  49. GRB 250419A: Mondy Continued Optical Observations
  50. GRB 250421B: AstroSat CZTI detection of a bright long burst
  51. EP250421a: Einstein Probe detection of an X-ray transient
  52. EP250421a: Mephisto optical counterpart confirmation
  53. EP250421a: JinShan likely optical counterpart
  54. The EP-WXT trigger 01709135179: Kinder optical counterpart candidate
  55. GRB 250419A: LCO optical observation
  56. GRB 250419A: JinShan optical observations
  57. GRB 250419A: SVOM/C-GFT optical observations
  58. GRB 250419A: Swift/UVOT Follow up
  59. GRB 250416C / EP250416a: SVOM/GRM observation of a burst
  60. GRB 250419A: LCO optical afterglow multi-band observations
  61. GRB 250419A: Mondy and AbAO Optical Observations
  62. GRB 250419A: AKO Optical Afterglow Detection
  63. GRB 250419A: VLT/X-shooter spectroscopic redshift z = 0.845
  64. GRB 250419A: GOTO optical counterpart detection
  65. GRB 250419A: KAIT optical afterglow observations
  66. GRB 250419A: SVOM/VT optical bright counterpart confirmation
  67. GRB 250419A: SVOM/COLIBRÍ (FM-GFT) Detection of the Optical Counterpart
  68. GRB 250419A: SVOM detection of a soft burst
  69. EP250416a: Swift/XRT counterpart fading
  70. EP20250416a: Swift/XRT counterpart detection
  71. IceCube-250416A: DDOTI Optical Observations
  72. EP250416a: Gemini South-GMOS optical counterpart
  73. SVOM/sb25041603 is not a GRB
  74. EP250416a: Einstein Probe detection of an X-ray transient
  75. SVOM/sb25041603: SVOM/COLIBRÍ (FM-GFT) Upper Limit on the Optical Counterpart
  76. IceCube 250414.324: DDOTI Optical Observations
  77. GRB 250413A: AstroSat CZTI detection
  78. EP250304a: ATCA radio observations
  79. GRB 250412A: AstroSat CZTI detection
  80. EP250404a: Nanshan 0.43m Telescope optical observatios
  81. GRB 250411A: DDOTI Optical Observations
  82. GRB 250314A: e-MERLIN observations
  83. GRB 250407A: Mondy and AbAO Optical Observations
  84. EP250227a: Further NOT optical observations
  85. GRB 250320B: cubesat Avion detection
  86. IceCube-250406A: Swift-XRT observations
  87. IPN triangulation of GRB 250321D (consistent with the fast X-ray transient EP250321a)
  88. IPN triangulation of GRB 250407A
  89. GRB 250407A: LCO detection of a fading optical counterpart
  90. EP250407a: Swift-XRT observations
  91. GRB 250407A: SVOM/GRM observation of a bright long burst
  92. GRB 250407A: EP-WXT afterglow detection
  93. EP250407a: EP-WXT detection of a fast X-ray transient
  94. GRB 250407A: COLIBRÍ/DDRAGO Detection of the Optical Counterpart
  95. GRB 250407A: KAIT Optical Afterglow Candidate
  96. IceCube-250406A: No candidates from the Zwicky Transient Facility
  97. GRB 250407A: Swift-XRT afterglow detection
  98. IceCube 250406A: DDOTI Optical Observations of the Refined Position
  99. IPN triangulation of GRB 250406B (short/hard)
  100. IceCube 250406.951: COLIBRÍ/DDRAGO Optical Upper Limit

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